There are a series of holes arranged on a conventional window curtain for facilitating a string to pass through. The obstruction to the light by a conventional window curtain as such is faulty in such a way that the curtain holes so arranged permit the light to pass through. In addition, the curtain holes so disposed could be used improperly as peep holes. In order to remedy the shortcoming mentioned above, a Y-shaped and folded window curtain impervious to light is made available, in which the curtain is first shaped into parallel grooves and ridges. The shoulders of a predetermined width extending outward from the ridge tops are so arranged that a series of shoulders are formed on the curtain. Located at the corresponding positions on a series of shoulders are curtain holes for accommodating a string to pass through, as shown in FIG. 1.
It must be stated unpretentiously that the Y-shaped and folded window curtain impervious to light mentioned above is by no means a product of recent introduction. However, the method and the apparatus available for its production in quantity at a low cost have not been introduced so far. Therefore, consumers at large have not been able to purchase the product as such at a reasonable and affordable price.